They suffered poisoning from hydrogen sulphide and were taken to hospital as a precaution.

It is thought the incident was sparked when a laboratory test went wrong at around 2.30pm on Wednesday.

The laboratory is run by Eurofins Environmental Testing in a building rented from Southern Water A specialist 'haz mat' team from Hampshire Fire and Rescue Service were called in along with crews from Eastleigh, service headquarters, St Mary's and Winchester.

The firefighters in protective clothing quickly determined that the gas had dispersed, said a spokesman today.

“The crews did a full survey and no gas was present. The 'haz mat' team was mobilised and it would have been treated as a potential chemical incident,” she said.

Watch manager Chris Roper, from Winchester Fire Station, said today: “I think the people went to hospital as a precaution to be tested. We had to go in to ensure the area had been ventilated. There was an escape of hydrogen sulphide gas when staff were testing samples. The gas is quite toxic.”

The noxious gas was dispersed through the building's internal ventilation and naturally by opening the windows.

Southern Water said the incident had nothing directly to do with them.

A spokesman said: “We are aware of this incident which occurred on land leased from us by Eurofins Environmental Testing.

“The company tests water samples for Southern Water and various other organisations and it was a sample for another company which is believed to have caused the problem.

“We understand the staff were treated at hospital and discharged the same day.”

Ipsoregulated

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